. "The comonomers include, for example, ??-olefins such as propylene, isobutylene, ??-octene and ??-dodecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid and itaconic acid, and their anhydrides, salts, or mono- or di-alkyl esters; nitrites such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefinsulfonic acids such as et" . . . .